/* ----------------------------------------------------------------------  
* Copyright (C) 2010 ARM Limited. All rights reserved.  
*  
* $Date:        29. November 2010  
* $Revision: 	V1.0.3  
*  
* Project: 	    CMSIS DSP Library  
* Title:        arm_fir_decimate_init_q15.c  
*  
* Description:  Initialization function for the Q15 FIR Decimator.  
*  
* Target Processor: Cortex-M4/Cortex-M3
*  
* Version 1.0.3 2010/11/29 
*    Re-organized the CMSIS folders and updated documentation.  
*   
* Version 1.0.2 2010/11/11  
*    Documentation updated.   
*  
* Version 1.0.1 2010/10/05   
*    Production release and review comments incorporated.  
*  
* Version 1.0.0 2010/09/20   
*    Production release and review comments incorporated  
*  
* Version 0.0.7  2010/06/10   
*    Misra-C changes done  
* ------------------------------------------------------------------- */ 
 
#include "arm_math.h" 
 
/**  
 * @ingroup groupFilters  
 */ 
 
/**  
 * @addtogroup FIR_decimate  
 * @{  
 */ 
 
/**  
 * @brief  Initialization function for the Q15 FIR decimator.  
 * @param[in,out] *S points to an instance of the Q15 FIR decimator structure.  
 * @param[in] numTaps  number of coefficients in the filter.  
 * @param[in] M  decimation factor.  
 * @param[in] *pCoeffs points to the filter coefficients.  
 * @param[in] *pState points to the state buffer.  
 * @param[in] blockSize number of input samples to process per call.  
 * @return    The function returns ARM_MATH_SUCCESS if initialization was successful or ARM_MATH_LENGTH_ERROR if  
 * <code>blockSize</code> is not a multiple of <code>M</code>.  
 *  
 * <b>Description:</b>  
 * \par  
 * <code>pCoeffs</code> points to the array of filter coefficients stored in time reversed order:  
 * <pre>  
 *    {b[numTaps-1], b[numTaps-2], b[N-2], ..., b[1], b[0]}  
 * </pre>  
 * \par  
 * <code>pState</code> points to the array of state variables.  
 * <code>pState</code> is of length <code>numTaps+blockSize-1</code> words where <code>blockSize</code> is the number of input samples  
 * to the call <code>arm_fir_decimate_q15()</code>.  
 * <code>M</code> is the decimation factor.  
 */ 
 
arm_status arm_fir_decimate_init_q15( 
  arm_fir_decimate_instance_q15 * S, 
  uint16_t numTaps, 
  uint8_t M, 
  q15_t * pCoeffs, 
  q15_t * pState, 
  uint32_t blockSize) 
{ 
 
  arm_status status; 
 
  /* The size of the input block must be a multiple of the decimation factor */ 
  if((blockSize % M) != 0u) 
  { 
    /* Set status as ARM_MATH_LENGTH_ERROR */ 
    status = ARM_MATH_LENGTH_ERROR; 
  } 
  else 
  { 
    /* Assign filter taps */ 
    S->numTaps = numTaps; 
 
    /* Assign coefficient pointer */ 
    S->pCoeffs = pCoeffs; 
 
    /* Clear the state buffer.  The size of buffer is always (blockSize + numTaps - 1) */ 
    memset(pState, 0, (numTaps + (blockSize - 1u)) * sizeof(q15_t)); 
 
    /* Assign state pointer */ 
    S->pState = pState; 
 
    /* Assign Decimation factor */ 
    S->M = M; 
 
    status = ARM_MATH_SUCCESS; 
  } 
 
  return (status); 
 
} 
 
/**  
 * @} end of FIR_decimate group  
 */ 
